Exposure assessments in reproductive and developmental toxicity testing: An IQ-DruSafe industry survey on current practices and experiences in support of exposure-based high dose selection.

The draft ICH S5(R3) guideline includes an exposure-based endpoint as an option for selecting the high dose in developmental and reproductive toxicity (DART) studies. In 2016, IQ DruSafe conducted an anonymous survey to identify industry practices and experiences related to pharmacokinetic assessments in DART studies in order to facilitate a pragmatic data-driven approach to development of an acceptable multiple of the clinical exposure to be proposed for dose selection in the guideline. Questions in the survey were designed to explore pharmacokinetic differences in pregnant versus non-pregnant animals, and to assess exposure levels attained in the absence of maternal toxicity as well as DART outcomes in animal studies associated with those exposures.

Allogeneic murine pregnancy models for assessing the developmental effects of immune-stimulating antibodies: Challenges in reproducibility.

Literature suggests that murine allogeneic pregnancy models are an alternative approach for evaluating the developmental toxicity of immune-stimulating agents. In this study, multiple syngeneic and allogeneic murine pregnancy models were used to assess the potential embryo-fetal effects of four different murine antibodies (IgG or IgG ) that activate the immune system by binding to T-cell receptors (PD-L1, LAG-3, and GITR). The pregnancy models were generated by within and between matings of five different inbred strains of mice (CBA/CaJ, DBA/2J, BALB/c, C57BL/6, and CBA/J).

Analysis of exposure margins in developmental toxicity studies for detection of human teratogens.

The draft Step 2 ICH S5(R3) guideline includes an exposure-based endpoint as an option for selecting the high-dose in reproductive and developmental toxicity studies. To help determine an appropriate exposure margin for embryofetal developmental toxicity testing, a retrospective analysis was undertaken to determine what threshold would have been sufficient to detect hazards to embryofetal development in rats and rabbits for 18 known and 4 presumed human teratogens. The analysis showed that using a high dose that provided at least a 6-fold exposure margin in the developmental toxicity studies would have been sufficient to detect the teratogenic hazard with relevance for humans for all these therapeutics.

Safety assessment of propylparaben in juvenile rats.

There are conflicting literature reports that parabens, useful antimicrobial additives in pharmaceuticals, may have estrogenic activity. We conducted a comprehensive study to determine whether propylparaben (PP) administration to juvenile rats is associated with adverse effects on reproductive development and function. PP was administered orally once daily to groups of Crl:CD(SD) rats at doses of 0 (vehicle), 10, 100, or 1,000 mg/kg on Postnatal Days (PNDs) 4-90.

Comparison of rat and rabbit embryo-fetal developmental toxicity data for 379 pharmaceuticals: on the nature and severity of developmental effects.

Regulatory non-clinical safety testing of human pharmaceuticals typically requires embryo-fetal developmental toxicity (EFDT) testing in two species (one rodent and one non-rodent). The question has been raised whether under some conditions EFDT testing could be limited to one species, or whether the testing in a second species could be decided on a case-by-case basis. As part of a consortium initiative, we built and queried a database of 379 compounds with EFDT studies (in both rat and rabbit animal models) conducted for marketed and non-marketed pharmaceuticals for their potential for adverse developmental and maternal outcomes, including EFDT incidence and the nature and severity of adverse findings.

Comparing rat and rabbit embryo-fetal developmental toxicity data for 379 pharmaceuticals: on systemic dose and developmental effects.

A database of embryo-fetal developmental toxicity (EFDT) studies of 379 pharmaceutical compounds in rat and rabbit was analyzed for species differences based on toxicokinetic parameters of area under the curve (AUC) and maximum concentration (C) at the developmental lowest adverse effect level (dLOAEL). For the vast majority of cases (83% based on AUC of n = 283), dLOAELs in rats and rabbits were within the same order of magnitude (less than 10-fold different) when compared based on available data on AUC and C exposures. For 13.

Assessment of cervical passage of vital dyes in pregnant, nonpregnant, and mated rats and mice.

Risk assessment for indirect exposure to small molecule pharmaceuticals in semen to the conceptus has traditionally been handled by calculations based on assumptions that any embryo-fetal exposure would be secondary to maternal absorption and redistribution. This study was designed to assess the potential for transcervical passage of drugs from semen. Reproductive tracts of rodents were examined following vaginal dosing with vital dyes during the estrous cycle, mating, and pregnancy.

Evaluation of early fetal exposure to vaginally-administered metronidazole in pregnant cynomolgus monkeys.

Given concern about potential embryo-fetal harm following seminal exposure to drugs with teratogenic potential, pharmaceutical companies use theoretical calculations to estimate seminal concentrations, maternal exposure, and distribution across the placenta to the embryo-fetal compartment for risk assessment. However, it is plausible that there are additional mechanisms whereby the conceptus is exposed. In order to determine if theoretical calculations are sufficiently conservative to predict embryo-fetal exposure from drugs in semen, pregnant cynomolgus monkeys were given a vaginal dose of metronidazole during the early fetal period and cesarean-sectioned.

Epididymal and systemic phospholipidosis in rats and dogs treated with the dopamine D3 selective antagonist PNU-177864.

Repeat dose oral toxicity studies were conducted in rat and dog to assess the safety for human clinical testing of the potent dopamine D3 receptor antagonist, PNU-177864. Systemic phospholipidosis was the principal treatment-related change with epididymal epithelial cell phospholipidosis being the most prominent finding in rats and dogs. Epididymal epithelial cells had no histologic evidence of degeneration; sperm density and morphology were normal histologically in both species; and sperm concentration, morphology, and motility in the dog were comparable to dogs given vehicle.